The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
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Diet Pop and Weight Loss — What You Need to Know
Diet pop (diet soda, diet cola) contains virtually no calories or sugar, so it won't directly cause weight gain like regular fizzy drinks. However, whether diet pop helps or hinders weight loss is more complex. Research suggests diet sweeteners may affect appetite regulation and weight management in different ways for different people. This guide explains the evidence, helps you understand how diet pop fits into a weight loss plan, and shows you how to track your actual weight loss progress using science-backed methods.
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Calculate Your BMI Instantly
Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
How Diet Pop Affects Weight Loss
Calorie content: Diet pop contains 0–5 calories per 330ml can — negligible compared to regular fizzy drinks (typically 140–160 calories). If you're aiming for a calorie deficit for weight loss, switching from regular to diet pop saves approximately 150 calories per can, or roughly 1050 calories per week.
- A weekly calorie saving of 1050 kcal could theoretically support losing approximately 0.15kg per week, assuming all other factors remain constant
- However, total calorie intake matters most — diet pop alone won't create the deficit needed for weight loss
- The NHS recommends losing 0.5–1kg per week through a sustained calorie deficit of 500–1000 kcal daily
Sweeteners and appetite: Some research suggests artificial sweeteners (aspartame, sucralose, stevia) may alter hunger signals or gut bacteria in ways that could affect appetite. Evidence is mixed — some studies show no effect on weight, others suggest modest associations with increased appetite. Individual responses vary significantly.
Clinically BackedWeight Loss
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How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
Diet Pop vs Regular Pop — And Your Weight Loss Plan
For weight management in the UK, the key difference is simple: diet pop has almost no calories, regular pop has many. One can of regular cola daily adds approximately 52,000 calories per year — equivalent to 7.3kg of body weight gain if no other changes are made. Switching to diet pop removes this excess entirely.
However, diet pop is not a weight loss solution on its own. Sustainable weight management requires a calorie deficit through diet and physical activity. If you're tracking your weight loss journey, use our free BMI calculator to set a healthy target weight, and then use our GLP-1 weight loss calculator to understand how prescription weight management options can support your goals alongside diet changes. Our progress tracker helps you log weekly weight changes and spot real trends.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
Does diet pop stop you from losing weight?
No — diet pop contains almost no calories and won't prevent weight loss. However, it won't cause weight loss either. Weight loss requires a calorie deficit, which you create through diet and exercise. If diet pop replaces regular fizzy drinks, that swap saves calories and can support weight loss efforts, but diet pop alone isn't a weight loss tool.
Can you drink diet pop while doing calorie restriction?
Yes. Diet pop fits within a calorie-restricted diet because it contributes virtually no calories. The key is your total daily calorie intake — as long as you maintain a deficit, diet pop won't harm progress. Some people find sugar-free drinks help satisfy cravings during weight loss without adding calories.
Is diet pop better than water for weight loss?
Water is always the healthier choice — it has no calories, no sweeteners, and supports hydration. Diet pop is fine occasionally but shouldn't replace water as your main drink. If you find diet pop helps you reduce regular fizzy drink consumption, it's a useful swap, but plain water is the NHS-recommended option.
Does diet pop affect metabolism or weight loss speed?
There's no strong evidence that diet pop significantly speeds up or slows down metabolism in ways that meaningfully affect weight loss. The artificial sweeteners may have minor effects on appetite in some people, but these are individual and typically small. Your overall calorie intake and activity level matter far more than whether you drink diet pop.
What's the best drink choice if I'm trying to lose weight?
Water is best for weight loss and hydration. Unsweetened tea and coffee are also calorie-free and fine in moderation. Diet pop can be an occasional choice if it helps you avoid regular fizzy drinks, but shouldn't be your main beverage. For sustainable weight loss, focus on total calorie intake — drinks should support that, not distract from it.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.